Description

Methyl Ethyl Ketone Peroxide (MEKP) is a highly reactive organic peroxide with the molecular formula C₈H₁₈O₆ and CAS number 1338-23-4. This compound, also known by its IUPAC name 2-hydroperoxy-2-(2-hydroperoxybutan-2-ylperoxy)butane, is widely utilized as a radical initiator in polymerization reactions, particularly in the curing of unsaturated polyester resins. MEKP is supplied as a clear, colorless to pale yellow liquid, typically dissolved in a phlegmatizer such as dimethyl phthalate for safe handling. It is available in various concentrations, with common commercial grades ranging from 30% to 60% active peroxide content.

MEKP is a critical component in the composites industry, offering excellent reactivity and curing performance at ambient temperatures. Its decomposition generates free radicals that initiate cross-linking reactions, making it indispensable for fiberglass-reinforced plastics (FRP), automotive parts, marine applications, and construction materials. Due to its hazardous nature, MEKP must be stored in a cool, well-ventilated area away from heat sources and incompatible materials. Proper personal protective equipment (PPE), including gloves and safety goggles, is required when handling this chemical.

Properties

• CAS Number: 1338-23-4
• Complexity: 146
• IUPAC Name: 2-hydroperoxy-2-(1-hydroperoxy-1-methyl-propyl)peroxy-butane
• InChI: InChI=1S/C8H18O6/c1-5-7(3,11-9)13-14-8(4,6-2)12-10/h9-10H,5-6H2,1-4H3
• InChI Key: WFUGQJXVXHBTEM-UHFFFAOYSA-N
• Exact Mass: 210.11033829
• Molecular Formula: C8H18O6
• Molecular Weight: 210.22
• SMILES: CCC(C)(OO)OOC(C)(CC)OO
• Topological: 77.4
• Monoisotopic Mass: 210.11033829
• Physical Description: Methyl ethyl ketone peroxide is a colorless liquid. Strong irritant to skin and tissue. Used as an initiator for room temperature cure of unsaturated polyester resins.
• Color/Form: Colorless liquid
• Odor: Typical odor-resembles that of acetone.
• Boiling Point: 244 °F at 760 mmHg
• Flash Point: 180 °F
• Solubility: 1 to 5 mg/mL at 72 °F
• Density: 1.17 at 68 °F – Denser than water; will sink
• Vapor Density: Component 2 (83.33%: LACTOSE): 6.69
• Vapor Pressure: less than 0.01 mmHg at 68 °F Component 2 (83.33%: LACTOSE)
• Stability/Shelf Life: UNSTABLE AGENT WHICH LIKE HYDROGEN PEROXIDE RELEASES OXYGEN.
• Autoignition Temperature: 1032 °F Component 2 (83.33%: LACTOSE)
• Synonyms: 2-BUTANONE PEROXIDE, 1338-23-4, Methyl ethyl ketone peroxide, Thermacure, Ketonox, Mepox, Esperfoam FR, 2-Butanone, peroxide, Lupersol DEL, Butanox LPT, 2-butanoneperoxide, Quickset super, Quickset Extra, Lucidol delta X, MEK peroxide, Kayamek A, Kayamek M, Lupersol DDM, Lupersol DNF, Lupersol DSW, Lupersol delta X, Permek G, Permek N, Sprayset MEKP, Chaloxyd MEKP HA 1, Lucidol DDM 9, Lupersol DDA 30, Trigonox M 50, Butanox M 50, MEKPO, Butanox M 105, Ethyl methyl ketone peroxide, HI-Point PD-1, HI-Point 90, Chaloxyd MEKP-HA 1, Chaloxyd MEKP-LA 1, HI-Point 180, Superox 46-710, RCRA waste number U160, Methylethylketonhydroperoxide, CCRIS 6216, Methyl ethyl ketone hydroperoxide, HSDB 4181, NCI-C55447, RCRA waste no. U160, EINECS 215-661-2, FR 222, W2545087UL, DTXSID1024671, 2-BUTANONE PEROXIDE [HSDB], dioxydibutane-2,2-diyl dihydroperoxide, 2-((2-hydroperoxybutan-2-yl)peroxy)butane-2-peroxol, 2-[(2-hydroperoxybutan-2-yl)peroxy]butane-2-peroxol, Lupersol Delta-X, 2butanone peroxide, HIPoint PD1, HIPoint 90, Chaloxyd MEKPHA 1, Chaloxyd MEKPLA 1, HIPoint 180, PERMEK H, Superox 46710, LUPERSOL DDM 9, LUPERSOL DHD 9, ethylmethylketone peroxide, methylethylketone peroxide, DELTA X 9, DIPROMETIL LA 50R, LUPERSOL DELTA X 9, MEPOX 55, DTXCID104671, CHALOXYD MEKP-HA 1,-LA 1, BUTANOX M50, M105, LPT, Methyl ethyl ketone peroxide (ACGIH), COMPONENT 2: DIMETHYL PHTHALATE, 2-butanone peroxide, MEKP, MEK peroxide, 2-Butanone peroxide (Luperox(R) DDM-9) solution, 2-Butanone peroxide (Luperox(R) DHD-9) solution, COMPONENT 1: 2-BUTANONE PEROXIDE (45%), 2-Butanone peroxide (Luperox(R) Delta X-9) solution, 215-661-2, MEKP, 2-hydroperoxy-2-(2-hydroperoxybutan-2-yldioxy)butane, UNII-W2545087UL, methyl ehtyl ketone peroxide, SCHEMBL15306, 2-Butanone peroxide, technical, 2-hydroperoxy-2-(2-hydroperoxybutan-2-ylperoxy)butane, CHEMBL1562553, AKOS015914484, NCGC00091754-01, NCGC00091754-02, NS00009405, A806682, Q2914590, 2-(dioxidanyl)-2-[2-(dioxidanyl)butan-2-ylperoxy]butane, Ethyl methyl ketone peroxide, Methyl ethyl ketone peroxide, 2-Butanone peroxide solution, ~32 wt. % in phthalate-free plasticizer mixture, 2-Butanone peroxide solution, ~35 wt. % in 2,2,4-trimethyl-1,3-pentanediol diisobutyrate

Application

Methyl Ethyl Ketone Peroxide (MEKP) is primarily used as a curing agent for unsaturated polyester resins in the production of fiberglass-reinforced plastics (FRP). It enables room-temperature curing, making it ideal for manufacturing boat hulls, automotive components, and construction panels. MEKP also serves as a radical initiator in polymerization reactions for specialty coatings and adhesives. Its fast reactivity and efficient cross-linking properties ensure high-quality, durable composite materials.

Safety and Hazards

GHS Hazard Statements

• H227: Combustible liquid [Warning Flammable liquids]
• H241: Heating may cause a fire or explosion [Danger Self-reactive substances and mixtures; Organic peroxides]
• H302: Harmful if swallowed [Warning Acute toxicity, oral]
• H315: Causes skin irritation [Warning Skin corrosion/irritation]
• H318: Causes serious eye damage [Danger Serious eye damage/eye irritation]
• H330: Fatal if inhaled [Danger Acute toxicity, inhalation]
• H335: May cause respiratory irritation [Warning Specific target organ toxicity, single exposure; Respiratory tract irritation]
• H336: May cause drowsiness or dizziness [Warning Specific target organ toxicity, single exposure; Narcotic effects]
• H370: Causes damage to organs [Danger Specific target organ toxicity, single exposure]
• H401: Toxic to aquatic life [Hazardous to the aquatic environment, acute hazard]

Precautionary Statements

• P210, P234, P235, P240, P260, P261, P264, P264+P265, P270, P271, P273, P280, P284, P301+P317, P302+P352, P304+P340, P305+P354+P338, P308+P316, P316, P317, P319, P320, P321, P330, P332+P317, P362+P364, P370+P378, P370+P380+P375[+P378], P403, P403+P233, P405, P410, P411, P420, and P501

Hazard Classes and Categories

• Org. Perox. D (90%)
• Acute Tox. 4 (92.6%)
• Skin Corr. 1B (91.4%)
• Eye Dam. 1 (77.7%)
• Acute Tox. 4 (30.4%)
• STOT SE 3 (29.8%)

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Disclaimer: Sold exclusively for laboratory research. Prohibited for commercial use, diagnostics, or human/animal applications. Buyers assume all compliance liability.